Java News from Wednesday, March 1, 2006

There is growing interest in running a variety of programming languages on the the Java platform, and consequently, on the Java virtual machine (JVM). This interest is increasingly focused on dynamically typed languages, in particular scripting languages.

To make it easier to produce performant, high quality implementations of such languages, we propose to add support at the virtual machine level.

Specifically, we seek to add a new JVM instruction, invokedynamic, designed to support the implementation of dynamically typed object oriented languages. We will also investigate support for hotswapping, the capability to modify the structure of classes at run time.

My big question is how this affects Java's security model, particualrly since "The invokedynamic instruction is in many ways similar to the existing invokevirtual instruction. However, it is much less constrained by byte code verification rules. Instead, it relies on dynamic typechecking to ensure the integrity of the virtual machine." This is scheduled for Java 7, Dolphin.
Comments are due by March 13. (Seems a bit short for such a major change.)

This specification will define a dynamic component framework including component lifecycle for existing Java SE platforms. The dynamic component model will support assembly of applications from components and support implementation detail hiding between components as well as lifecycle management of those components.

The specification will be built upon capabilities in existing Java SE platforms and provide a consistent and predictable dynamic component model across the family of Java platforms in conjunction with JSR 232 for Java ME (CDC).

The specification will enable components to be declared through metadata and be assembled at runtime using a class loader delegation network. The specification will also allow components to be dynamically life cycle managed (install, start, stop, update, uninstall).

This is intended to run on Java 1.2 and later, so despite the coincedental timing and use of the word "dynamic" in the title, I don't think it has much to do with JSR-292.
Comments are due by March 13.